Zoom level in iTowns

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Context

In WMTS, The zoom level The zoom represents a resolution in px/meter (visiting).

In iTowns, the zoom level is used to displayed the correct data in function of camera position.

By example, for each tile extent is added the zoom level of tile. It is then used to determine the zoom level of a texture that doesn't have a tiled extent (WMTS).

Motivation

Remove zoom level concept from iTowns core. Because it's not suitable for all cases and thus complicates the process and providers.

Possible Cause/Fix/Solution

It should be possible to replace the zoom level by the resolution. This resolution is computable, for all images, because it is obtained by dividing its pixel dimension by its extent in meters (or degrees).